Eric Crumpton observed something unexpected when he began replacing bridles and anchor chains on a portion of the deepwater pipeline at the Natural Energy Laboratory of Hawaii Authority last month.

“This (project) is fantastic because of the clarity of the water,” said Crumpton, the remotely operated vehicles operations manager for Global Diving and Salvage out of Seattle. “We’re operating without lights during the day. (Hawaii) is the only place I’ve ever seen it (that light at 500 feet deep).”

Crumpton’s crew, aboard a barge anchored off the North Kona coastline, works around the clock, seven days a week, to fit the new bridles, which help hold the pipeline to the ocean floor, and chains.

NELHA Executive Director Gregory Barbour said Global Diving and Salvage and others working on the project were hoping for good weather while the remotely operated vehicles, which use thrusters to stay in place despite strong currents and use little robotic arms to do the repairs, were underwater.

“It’s so difficult to work at those depths,” Barbour said. “They’re prepared for anything to happen.”

The control room, he said, looks like something from NASA.

“They’re taking bolts on and off (with the remotely operated vehicles),” Barbour said, describing some of the work. “Trying to cut an old chain. They have to have a lot of patience.”

Workers gave Barbour a comparison to explain how much harder the work is underwater. What would take about half an hour to cut through with a hacksaw on dry land takes about four hours under water, Barbour said.

One of the remotely operated vehicles, called a Falcon, is a small inspection machine with cameras and a small mechanical arm, said NELHA Operations Manager Jan War, who has been overseeing work as the officer in charge for the $4.7 million project. The other, called a Cougar, is much larger, fitting into the work class category, with two multifunction mechanical arms and hands, several cameras and lights.

The work is being completed on NELHA’s 40-inch deep-seawater pipe, which was laid in 1986. Barbour said the work is all being done to the pipe’s exterior and isn’t causing disruptions for NELHA tenants.

The work should extend the system’s life another 15 to 20 years, he added. Surveys of the pipeline showed the mooring bridles and transition anchors were beginning to deteriorate.

The Legislature appropriated the funds in 2011 and 2012.

In addition to resecuring the pipe to the ocean floor, the project added buoyancy. NELHA contracted with Honolulu’s Healy Tibbits Builders Inc. for the project.

“It’s something we’ve wanted to do for a while,” Barbour said, adding officials wanted to do the work in the summer, when the weather and surf were likely to be calmer.